TY - JOUR AB - Highly directive antennas with the ability of shaping radiation patterns in desired directions are essential for efficient on-chip optical communication with reduced cross talk. In this paper, we design and optimize three distinct broadband traveling-wave tantalum pentoxide antennas exhibiting highly directional characteristics. Our antennas contain a director and reflector deposited on a glass substrate, which are excited by a dipole emitter placed in the feed gap between the two elements. Full-wave simulations in conjunction with global optimization provide structures with an enhanced linear directivity as high as 119 radiating in the substrate. The high directivity is a result of the interplay between two dominant TE modes and the leaky modes present in the antenna director. Furthermore, these low-loss dielectric antennas exhibit a near-unity radiation efficiency at the operational wavelength of 780 nm and maintain a broad bandwidth. Our numerical results are in good agreement with experimental measurements from the optimized antennas fabricated using a two-step electron-beam lithography, revealing the highly directive nature of our structures. We envision that our antenna designs can be conveniently adapted to other dielectric materials and prove instrumental for inter-chip optical communications and other on-chip applications. AU - Farheen, Henna AU - Yan, Lok-Yee AU - Quiring, Viktor AU - Eigner, Christof AU - Zentgraf, Thomas AU - Linden, Stefan AU - Förstner, Jens AU - Myroshnychenko, Viktor ID - 31329 IS - 11 JF - Optics Express KW - tet_topic_opticalantenna SN - 1094-4087 TI - Broadband optical Ta2O5 antennas for directional emission of light VL - 30 ER -